Mammal Species at Risk

San Francisco Dusky-footed Woodrat Neotoma fuscipes annectens (FSC, CSC) The San Francisco dusky-footed woodrat is one of 11 subspecies that live in California and the arid west. They are medium-sized rodents, about the size of an adult rat, with a body around 7 inches long, nose to rump, and a furred tail. They live in a variety of brushy and forested habitats. Woodrats are relatively common and widespread in our bioregion, but their complex social structure makes them particularly vulnerable to disturbance. A different subspecies found elsewhere, the riparian woodrat (N. f. riparia) has been listed as Endangered on the federal list because of habitat loss and disturbance. Woodrats build mounded stick lodges that may range in size from 3 to 8 feet across at the base and as much as 6 feet tall, and they tend to live in colonies of 3 to 15 or more lodges. The lodges or houses can be quite complex inside, with multiple chambers for general living, nesting, latrine use, food storage, and other activities. The availability of suitably-sized sticks may limit the number of woodrat houses. Each house is occupied by a single adult; adult females share the nest with their litters for a few months until the young disperse to nearby nests. Adult female woodrats live in the same nest until they die, when the nest is taken over by one of the female offspring. In this manner nests may be occupied and maintained by the same family for decades. Individual lodges may persist for 20 to 30 years. Reptiles, amphibians, small mammals, and invertebrates are frequent commensals with the woodrats, sharing the lodges for shelter. Woodrat nests provide protection from temperature and moisture extremes and allow animals that might not otherwise tolerate local conditions to live there, increasing the biotic diversity.

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